U.S. patent number 4,578,586 [Application Number 06/574,538] was granted by the patent office on 1986-03-25 for chemical agent monitor and alarm device.
This patent grant is currently assigned to Her Majesty the Queen in right of Canada, as represented by the Minister. Invention is credited to Jonathan M. Preston.
United States Patent |
4,578,586 |
Preston |
March 25, 1986 |
Chemical agent monitor and alarm device
Abstract
The specification describes a case for use with a hand-portable
chemical agent detector for continuously monitoring an atmosphere
for the presence of predetermined chemical agents. The detector
having means for ionizing air samples and providing at an output
terminal electrical signals representative of the mobility spectrum
of ionized chemical vapors produced by the ionizing means. The case
comprises means defining a chamber in the case for supporting and
removably enclosing the detector, means for communicating ambient
atmosphere to the chamber, electrical circuit means in the case,
the circuit means being adapted to be detachably connected to the
detector output terminal when the detector is positioned in the
chamber and being responsive to the electrical signals for
producing an alarm signal when the signals detect a chemical agent
concentration in the atmosphere exceeding a predetermined
concentration level, and alarm means responsive to the alarm
signal.
Inventors: |
Preston; Jonathan M. (Ottawa,
CA) |
Assignee: |
Her Majesty the Queen in right of
Canada, as represented by the Minister (Ottawa,
CA)
|
Family
ID: |
26285683 |
Appl.
No.: |
06/574,538 |
Filed: |
January 27, 1984 |
Foreign Application Priority Data
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Mar 30, 1983 [GB] |
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8308783 |
Sep 30, 1983 [GB] |
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8326205 |
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Current U.S.
Class: |
250/382;
250/336.1; 250/389; 340/691.5; 340/691.6; 340/693.1; 340/693.5;
73/431; D10/46 |
Current CPC
Class: |
G08B
21/14 (20130101); G08B 21/12 (20130101) |
Current International
Class: |
G08B
21/00 (20060101); G08B 21/12 (20060101); G08B
21/14 (20060101); G01T 001/18 (); G01D 011/24 ();
G08B 023/00 () |
Field of
Search: |
;250/282,287,379,381,382,386,387,388,336.1,526,288,389
;324/464,465,469 ;73/431,864.34 ;D10/106,81 ;374/208
;340/632,693 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1573678 |
|
Aug 1980 |
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GB |
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1596916 |
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Sep 1981 |
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GB |
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Other References
"Plasma Chromatography of Phosphorus Esters", by J. M. Preston et
al-Analytical Chemistry, vol. 49, No. 12, Oct. 1977. .
"Plasma Chromatography", by Francis W. Karasek from Analytical
Chemistry, vol. 45, p. 710A, Jul. 1972. .
Technical Paper No. 264, entitled "The Detection of Mustard Agent
Vapour Using Ion Mobility Techniques (U)", by D. A. Blyth, dated
Jan. 1980. .
Brochure entitled "Chemical Agent Monitor", by Graseby Dynamics
Ltd., dated 10/82..
|
Primary Examiner: Smith; Alfred E.
Attorney, Agent or Firm: Hayes, Davis & Soloway
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. Apparatus for use with a hand-portable chemical agent detector
for continuously monitoring an atmosphere for the presence of
predetermined chemical agents, said detector having means for
ionizing air samples and providing at an output terminal electrical
signals representative of the mobility spectrum of ionized chemical
vapours produced by said ionizing means, said apparatus
comprising:
means defining a chamber in said apparatus for supporting and
removably enclosing said detector;
means for communicating ambient atmosphere to said chamber;
electrical circuit means in said apparatus, said circuit means
being adapted to be detachably connected to said detector output
terminal when said detector is positioned in said chamber and being
responsive to said electrical signals for producing an alarm signal
when said signals detect a chemical agent concentration in said
atmosphere exceeding a predetermined concentration level; and
alarm means responsive to said alarm signal.
2. Apparatus as defined in claim 1, said alarm means including a
visual indicator mounted on the exterior of said enclosure.
3. Apparatus as defined in claim 1, said alarm means including an
audible indicator mounted in said enclosure.
4. Apparatus as defined in claim 1, said circuit means being
further responsive to said signals for producing a further signal
representative of the identity of a detected chemical agent and
display means mounted on said apparatus and responsive to said
further signal for displaying the identity of said detected
chemical agent.
5. Apparatus as defined in claim 4, said detector ionizing means
including electrical circuit means having an independent d.c.
source of power, said apparatus further including a d.c. source of
power mounted therein, and means for connecting said detector
electrical circuit means to said source of power in said apparatus
when said detector is disposed in said chamber.
6. Apparatus as defined in claim 5, said electrical circuit means
in said apparatus including means for periodically reversing the
polarity of said voltage applied to a drift region in said
detector.
7. Apparatus as defined in claim 6, said apparatus including an
external connector mean for selectively connecting said electrical
circuit means in said apparatus to an external source of power.
8. Apparatus as defined in claim 1, said apparatus being adapted
for removably supporting a remote alarm adapted to be connected to
the alarm signal output of said circuit means.
9. Apparatus as defined in claim 1, further including, in
combination, remote display means adapted to be electrically
connected to said electrical circuit means for selectively
actuating said circuit means from a location remote from said
apparatus, said remote display means having alarm means responsive
to said alarm signal.
10. Apparatus as defined in claim 9, said circuit means having
means for periodically reversing the polarity of the voltage
applied to a drift region in said detector, and said remote display
means further including means for selectively activating said
polarity reversing means.
11. Apparatus as defined in claim 1, said apparatus further
including:
a body portion having a bottom wall adapted to be supported on a
generally horizontal support surface, and integral upstanding side
walls extending from said bottom wall and terminating in a first
edge means, said bottom wall and said side walls having
substantially uninterrupted exterior surfaces merging smoothly into
one another and means in said first body portion for removably
supporting said detector in a predetermined angular position with
respect to said bottom wall; and
a lid portion having a top wall and integral side walls depending
from said top wall and terminating in second edge means arranged
for abutting and mating engagement with said first edge means, said
top and side walls having substantially uninterrupted exterior
surfaces merging smoothly into one another, said lid portion being
adapted to be movably mounted on said first body portion in edge to
edge abutting engagement and define therewith an interior chamber
for enclosing said detector, said lid portion having air inlet
means for admitting ambient air into said chamber.
12. Apparatus as defined in claim 11, said means for removably
supporting said detector including an electrical connector secured
to said body portion and adapted to be detachably connected to a
detector electrical connector having said output terminal.
13. Apparatus as defined in claim 12, said means for removably
supporting said detector including a partition removably supported
on said body portion side walls adjacent said first edge means and
defining with said body portion a second chamber for enclosing said
electrical circuit means and a d.c. source of power for said
circuit means, said partition including a recess extending into
said second chamber for receiving, at least in part, and supporting
said detector at an angle to said bottom wall.
14. Apparatus as defined in claim 13, said electrical connector of
said apparatus being secured to said partition within said
recess.
15. Apparatus as defined in claim 13, said partition having a
further recess adapted to removably receive a remote alarm.
16. Apparatus as defined in claim 15, said electrical circuit means
including an external power connector secured to one of said body
portion side walls for selective detachable connection of said
electrical circuit to an external source of power, and a remote
alarm connector secured to one of said body portion side walls for
selectively communicating said alarm signal to a remote alarm.
17. Apparatus as defined in claim 16, said alarm means including a
visual indicator mounted in said top wall of said lid, an audible
indicator mounted in said body portion, and a remote alarm adapted
to be connected to said remote alarm connector.
18. A chemical agent detecting and alarm apparatus for detecting
the presence of predetermined chemical agents in an atmosphere and,
if present, the concentration thereof, said apparatus being adapted
to be used in a manual mode for analyzing vapours emanating from
surfaces and the like suspected of being contaminated by said
chemical agents and in an automatic mode for continuously
monitoring ambient air, said apparatus comprising, in
combination:
a hand-portable chemical agent detector having a housing, a chamber
in said housing for ionizing air samples drawn thereinto, a rigid,
air inlet probe for communicating ambient air samples to said
chamber, an outlet for exhausting said samples from said chamber,
pump means for admitting and exhausting said samples into and from
said chamber, means responsive to ions produced in said chamber for
producing a signal representative of the mobility spectrum of said
ions, means responsive to said signal for determining the
concentration and identity of chemical in said samples for
producing an output signal representative thereof, display means
responsive to said output signal for displaying the concentration
and identity of detected chemical agents, a connector for
outputting said signal produced by said ion responsive means, and a
d.c. power supply in said housing for activating electrical
circuitry in said detector during use of said detector in said
manual mode;
a case for removably enclosing said detector, said case having a
main body portion and a lid defining a chamber with said body
portion, means within said chamber for detachably connecting said
detector to said main body portion, said lid being movable between
an opened position whereat said detector may be inserted into and
removed from said chamber and a closed position for enclosing said
detector, means in said lid for admitting ambient air into said
chamber, electrical circuit means in said case having an electrical
connector adapted to be detachably connected to said detector
connector, said case electrical circuit means being responsive to a
signal at said connector for determining the concentration of
detected chemical agents and producing an alarm signal when a
detected concentration exceeds a predetermined threshold, a d.c.
power supply in said main body means for said electrical circuit
means and means for connecting said power supply to said means for
producing said mobility spectrum when said detector is disposed in
said chamber; and
remote display means for selectively activating said circuit means
from a location remote from said case, said display means including
alarms means responsive to said alarm signal;
said detector being operable in said manual mode independently of
said case and said display means, and said detector, said case and
said display means being operable as a unit in said automatic mode.
Description
This invention relates to a chemical agent detector and alarm.
BACKGROUND OF THE INVENTION
Chemical agent detecting and alarm devices are devices which have
been developed for use by armed personnel in the event of chemical
warfare to detect the presence of chemical agents or vapours and
activate an alarm when the concentration of a detected agent
exceeds a predetermined safe level.
The instruments are designed to subject an air sample to tests
which detect the presence and concentration of certain chemical
agents of interest and activate an alarm when the tests reveal an
unsafe concentration. The devices are used in essentially two
modes. In an automatic mode, they are used as standalone units at a
desired site to continuously monitor ambient atmosphere at that
site. A remote alarm may be connected to a device for communicating
the alarm signal to another site. In a manual mode, they are
carried by a user and manipulated to sample air immediately
adjacent surfaces suspected of being contaminated. In order to
conveniently facilitate the latter, the devices must be relatively
light and portable.
While portable, many conventional devices tend to be sufficiently
heavy and awkward that they cannot be conveniently and comfortably
carried in one hand of a user and, thus, have tended to assume
backpack configurations for use in the manual mode discussed above.
Flexible tubes manipulated by the user extend from the backpacks
for supplying air samples to the devices. Not only does this
arrangement make the various meters on the instrument difficult for
the user to read, the flexible tubes tend to absorb chemical agents
which results in a reduction of both the response speed and
sensitivity of the devices.
Some conventional devices utilize chemical tests to determine the
identity and concentration of chemical agents in air samples. This
places significant limitations on the number and type of chemical
agents which can be monitored within the framework of a relatively
light, portable device because the necessary apparatus and
chemicals are space consuming and relatively heavy. In addition,
the tests render the devices relatively complex in terms of design,
structure, operation and maintenance. A particularly important
consideration insofar as maintenance is concerned is the
decontamination of devices which have been exposed to chemical
agents. Chemical agents tend to display low surface tension
properties and thus tend to migrate to sharp corners, joints and
like discontinuities on exposed surfaces. Devices having relatively
complex mechanical designs thus tend to be difficult to
decontaminate.
A recently developed chemical agent detecting device overcomes many
of the aforementioned drawbacks. Structurally, the device is
extremely light and compact so that it can be comfortably and
conveniently carried in one hand by a user. A rigid, tubular probe
extends from one end of the device and serves as an inlet for
admitting air samples into the device. Thus, the device is easily
manipulated, the displays are readily accessible to the user and
there is little, if any, absorption of chemical agents by the
probe.
The device makes use of ion mobility principles to determine the
identity and concentration of chemical agents of interest. In
essence, the air samples drawn into the unit are ionized to produce
primary positive and negative ions. The ions undergo complex ion
molecule reactions which result in a mixture of ions and ionic
clusters which are urged to a collector in the device. The
differences in mobilities of the ions and ionic clusters result in
different arrival times at the collector. The collector current as
a function of time represents a mobility spectrum for the sample.
Each peak is indicative of a particular chemical agent or species.
The drift time indicates the identity of the species and the
magnitude indicates the concentration of the species. After
amplification, the collector current is fed to a microprocessor
which determines the identity of the species represented by each
peak on the basis of the drift time and the concentration of the
species based on the height of the peak and causes this information
to be output to a display.
While the latter device is highly suited for use in the manual
mode, it is not particularly well suited for use in the automatic
mode because it cannot be constructed to rest on a support surface
in the proper position without hampering its use in the manual
mode, it is fragile and therefore susceptible to damage if left
unattended and cannot be provided with sufficient battery capacity
to enable it to be used continuously for extended periods of
time.
SUMMARY OF THE INVENTION
The present invention seeks to overcome the disadvantages of
devices of the type just described by providing a case which not
only supports and protects the chemical agent detector during
storage, but enables the detector to be used in the automatic mode
and which functions as an alarm responsive to the detector
output.
Generally, the present invention provides a case for use with a
hand-portable chemical agent detector for continuously monitoring
an atmopshere for the presence of predetermined chemical agents,
the detector having means for ionizing air samples and providing at
an output terminal electrical signals representative of the
mobility spectra of ionized chemical vapours produced by the
ionizing means. The case comprises means defining a chamber in the
case for supporting and removably enclosing the detector, means for
communicating ambient atmosphere to the chamber, electrical circuit
means in the case, the circuit means being adapted to be detachably
connected to the detector output terminal when the detector is
positioned in the chamber and being responsive to the electrical
signals for producing an alarm signal when the signals detect a
chemical agent concentration in the atmosphere exceeding a
predetermined concentration level, and alarm means responsive to
the alarm signal.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more apparent
from the following description in which reference is made to the
appended drawings wherein:
FIG. 1 is a perspective view of the apparatus of the present
invention illustrating the case in an opened condition;
FIG. 2 is a longitudinal cross-sectional view, taken along line
2--2 of FIG. 4, of the case in a closed condition with the detector
operatively disposed in the case;
FIG. 3 is an end view of the case;
FIG. 4 is a top view of the case with its lid in an opened
position;
FIG. 5 is a block diagram view of an electrical circuit of the
present invention; and
FIG. 6 is a perspective view of an alternative construction of the
case and the detector.
DESCRIPTION OF A PREFERRED EMBODIMENT
The drawings illustrate a chemical agent detector and alarm unit 10
for use with a chemical agent detector 12 (FIGS. 2, 5 and 6).
Detector 12 does not itself constitute the present invention.
However, a brief description of its construction and operation is
included hereinbelow with reference to FIGS. 2, 5 and 6 in order to
facilitate understanding of the present invention.
Detector 12 is a light and compact device which can be comfortably
carried in one hand by a user. The unit includes a tubular,
parallelepiped casing 14 having a handle 16 which extends from the
casing in a generally parallel fashion and which serves as a
housing for a cylindrical battery (not shown). A rigid tubular
probe 18 extends axially from one end 20 of the casing and defines
a sample flow air inlet passage 22. A sample flow outlet passage 24
is formed adjacent the probe.
The casing is formed with an analyzing chamber 30 having a membrane
31 which preferentially passes agents and blocks water and other
atmospheric gases, an ionization region 32 in which a suitable
ionizing source 34 is mounted, and a drift region 36. The ionizing
source may be a radioactive source or means for generating an
appropriate electrical discharge. A closed-circuit path circulates
carrier gases through the analyzing chamber by means of suitable
pumps (not shown) which also effect the flow of sample gas. A
collector 38 is disposed at the end of the chamber remote from
probe 18.
As the carrier gas containing agent, if it is present in the
atmosphere, flows through the ionization region, primary positive
and negative ions are produced. Thereafter, a series of ion
molecule reactions take place to produce a mixture of ions and
ionic clusters. The charged species are electronically pulsed into
the drift region towards collector 38. Differences in the mobility
of the ions result in different arrival times at the collector. The
collector current represents the mobility spectrum for the sample.
Each peak of the mobility spectrum represents a particular chemical
agent. The drift time associated with each peak is indicative of
the identity of the agent while the magnitude or height of the peak
is indicative of the concentration of the agent.
The collector current is amplified and fed to a detection circuit
40 which, for each detected peak, compares the component of the
signal representing the drift time against predetermined drift
times for known, chemical agents and activates a display 42 to
indicate the identity of the detected species if a match is made.
Circuit 40 also determines the concentration of the species on the
basis of the component of the signal representing the height of the
peak for output to display 42. A polarity switch 44 is provided for
selective actuation by the user for periodically switching the
polarity of the voltage source in the detector in order to monitor
both positive and negative ions produced.
Devices of the above described type are known and, accordingly,
detector 12 will not be described in further detail. However,
further particulars of the construction and operation of devices of
this type may be obtained by reference to British Patent
Specifications Nos. 1,573,678 published Aug. 28, 1980 and 1,596,916
published on Sept. 3, 1981, both of which have been assigned to Pye
(Electronic Products) Limited.
While the above described detector is well suited for manual use in
analyzing surfaces, it is not as well suited for monitoring
atmospheric air in an unsupervised condition. For example, the
device cannot simply be placed on the ground at a site at which it
is desired to monitor the atmosphere because the boundary layer of
grass, bushes and the like may adversely affect the output of the
device. Modification of the structure of the unit such that its
inlet probe is kept above the boundary layer when used in the
automatic mode would render the resulting device cumbersome to use
in the manual mode. In addition, the device cannot be provided with
sufficient battery capacity to permit it to be used for extended
periods of time in the automatic mode. The present invention
provides a case for use with a detector of the aforementioned type
so that the detector is rendered suitable for use in an unattended,
atmospheric air monitoring mode. Additionally, the present
invention seeks to provide a case which functions as an alarm which
is responsive to the electrical output of the detector.
With particular reference to FIGS. 1-4, detector and alarm unit 10
includes a case 50 having a first body portion or base 52, a second
body portion or lid 54, and a pair of handles 56, 56 pivotally
mounted on opposed side walls of the base. FIG. 2 illustrates the
detector operatively disposed in the base for use of the
combination in an atmospheric air monitoring mode.
Base 52 is comprised of a generally rectangular bottom wall 60 from
which extend a pair of opposed, upstanding planar side walls 62, 64
and a pair of opposed, upstanding, planar end walls 66, 68. The
opposed walls diverge upwardly and outwardly. The side and end
walls terminate in a marginal edge 70 disposed in a plane which
substantially parallels bottom wall 60. As best shown, in FIGS. 1-3
the side, end and bottom walls are substantially uninterrupted and
the external corners of the base are rounded to minimize sites to
which chemical agents might migrate and collect. An internal
shoulder 72 is formed on the inner side of the side and end walls
and is slightly spaced from edge 70 so as to form a support for a
partition or panel 74 on which the detector is mounted. The panel
is removably secured to the base by means of screws 75 threaded
into the shoulder. The base and panel together define a chamber 76
which contains electrical circuitry 78 and a relatively high
capacity d.c. battery (FIG. 5).
Each handle 56 includes a grip portion 80 and a pair of wire-like
arms 82 and 84 whose free ends 86 and 88, respectively, are
received in longitudinally extending blind holes 90 and 92 formed
in embossments 94 and 96 in the side wall adjacent the bottom wall
of the casing. Thus, as best shown in FIG. 3 the handles are
adapted to pivot transversely of the casing between a carrying
position in which the handles overlie the lid and maintain it in a
closed position and a spread position which permits the lid to be
opened and the detector to be inserted or removed. The handles
and/or lid may be arranged to be releasably secured to one another
if so desired.
A jack 100 for an external power source, and a jack 102 for a
remote display unit are secured to end wall 66 of the base.
With reference to FIGS. 1, 2 and 4, panel 74 is removably secured
to the base in order to permit mounting and/or replacement of
component parts of electrical circuitry 78. The panel is of
unitary, generally planar construction and formed with a recess 110
shaped to receive the detector in a snug fit relation. The recess
has a bottom wall 112 which is inclined with respect to the bottom
wall of the base, a back wall 114 which extends substantially
perpendicularly from bottom wall 112 and a pair of side walls 116,
118 which diverge slightly from one another. A jack 120 is secured
to back wall 114 for electrical connection of circuitry 78 to the
circuitry of the detector. Recesses may be formed in panel 74 for
removably receiving a remote alarm unit, a confidence-giving test
kit, a rain shield for the probe inlet, and other ancillary
equipment (not shown).
The detector is provided with a plug 46 adapted to be detachably
connected to jack 120 for providing electrical communication
between the detector circuitry and the casing circuitry. The plug
is located on back wall 48 of the detector and the position of jack
120 in back wall 114 of the recess corresponds with the position of
plug 46 in back wall 48 of the detector so that, when inserting the
detector in the casing, the detector is placed upon bottom wall 112
of the recess and slid therealong until the plug and jack matingly
interconnect. Conversely, when removing the detector, it is simply
slid upwardly along bottom wall 112. The detector is disposed in an
inclined position so that its probe is removed from the boundary
air layer of grass, bushes and the like which may exist at the site
at which the device is used in the automatic mode.
Also secured to panel 74 is a liquid crystal display (LCD) 122, for
dislaying the identity and concentration of detected chemical
agents, a rotary switch 178 for selecting a horn 172 or light 174
or both, and a rotary switch 180 for setting the
amplitude/intensity (cannot be zeroed) of the horn and light.
Lid 54 is arranged to be pivotally connected to the base along the
edge portion of end wall 68 thereof and includes a stepped top wall
130, forwardly and rearwardly sloping, planar front and rear walls
132, 134, respectively, and diverging side walls 136 and 138. The
end and side walls terminate in an edge 140 sized to abuttingly
engage edge 70 of the base. As with the base, the walls of the lid
are generally planar and substantially uninterrupted and the
corners are rounded in order to facilitate decontamination. The
base and lid together define a second chamber 142 which houses the
detector when the lid is in its closed position. Front wall 132 is
formed with an aperture 144 for communicating ambient air to the
detector within chamber 142 when the device is used in the
atmospheric air monitoring mode.
Light 174 is mounted in a lens 176 formed in the upper portion of
top wall 130. The lens is integral with the top wall and smoothly
merges into the planar surface of the wall as shown in order to
facilitate decontamination of the top wall of the lid.
With reference to FIG 1, the apparatus also includes a remote
display unit 200 for passing a warning of the presence of agents to
another location such as inside a vehicle or shelter, or a tactical
location. Unit 200 is connected to the case by means of appropriate
electrical wire 202 connectable with jacks 102. The remote display
unit includes a light 210 and a horn 212 controlled by switches 206
and 208 which function identically to light 174 and horn 172 with
switches 178 and 180. It also includes a liquid crystal display 214
which functions identically to LCD 122. Switch 206 has positions
for shutting off the remote display unit and for testing its
operation. In an alternate embodiment of the invention, the display
components 210, 212, 122, and their switches 178 and 180 are not
present and only the remote display unit is used for warning.
FIG. 5 is a block diagram illustration of the electrical circuitry
78 of detector and alarm unit 10 and a diagrammatical
cross-sectional view of detector 12. The detector is shown as
having an output line 150 for communicating the amplified collector
current to circuitry 78 via plug 46 and jack 120. When mounted in
the case, the detector is connected to and powered by a power
conditioner 152 via input line 154, which leads to and from an
ON/OFF switch via jack 102, and to a polarity relay driver 156 via
line 158. One input of power conditioner 152 is connected to jack
100 while another input is connected to an internal battery pack
153. Line 158 is connected, via plug 46 and jack 120, to the input
of a polarity relay 160 added to the detector.
A first circuit 164 is responsive to the component of the signal in
line 150 which represents the drift time of the peak or peaks by
producing a signal which is representative of the identity of the
chemical agent indicated by the peak and actuates a display driver
162, which, in turn, actuates a display 122. More specifically,
circuit 164 compares the component of the signal representing the
drift time(s) against each of a number of signals representing the
drift times of known chemical agents. The output is produced when a
match occurs.
A second circuit 166 is responsive to the component of the signal
in line 150 which represents the height of the peak or peaks by
calculating the concentration of the chemical agent indicated by
the peak or peaks and supplies an appropriate signal to display
driver 162, which, in turn actuates display 122. The display of the
concentration may be in digital form providing a numerical value of
the concentration or in the form of a series of sequentially
operated lights or the like providing a semi-quantitative
indication of the concentration.
A third circuit 168 compares the concentration determined by
circuit 166 against a predetermined threshold level for the
chemical agent identified by circuit 164 and provides an output
signal along line 170 to horn 172, light 174 and a remote alarm
driver 175 when the threshold is exceeded. The outputs of the three
circuits are passed to the remote display unit 200 through jack
102. Telemetry techniques are used to pass the following
information: alarm/no alarm, fault/no fault, (self-diagnostic
check) agent identification, agent concentration, fault
identification (such as low battery power).
A fourth circuit 182 is connected to polarity relay driver 156 via
line 183 and switch 185. Circuit 182 is in the form of timer which
provides an output on a cyclical basis so as to correspondingly
effect a change in the polarity of the voltage source activating
the detector circuitry. In this manner, it is possible to monitor
both positive and negative ions which may be produced. The duty
cycle may have any suitable value. Circuit 182 may be deactivated
by switch 185 in the event that it is desired to monitor only
positive ions.
Circuits 164, 166, 168 and 182 are comparable to circuitry
developed for detector 12 and thus need not be described in further
detail.
As mentioned, the device may be operated in a manual mode and an
automatic mode. In the manual mode, the detector is used
independently of the detector and alarm unit 10, is disconnected
from jack 120 and operates under its own power. When the probe is
positioned adjacent a surface to be tested, the detector draws in a
sample of air from adjacent the surface and produces and feeds an
electrical signal to the microprocessor circuit 40 which in turn
activates the display.
In the automatic mode, the detector is placed within recess 110 of
the case in the manner previously explained. The lid is closed and
latched by handles 56. If desired, an external power source may be
connected to jack 100. The remote display unit is connected to jack
102 if desired. The case is then placed at a desired monitoring
site.
When it is desired to store the combination, the detector is placed
in recess 110 of the casing. The lid is closed and the handles are
moved to their overlying position. It will be seen from the
foregoing, therefore, that the present invention provides a light
and compact device which can readily be used in the manual and
automatic modes and which includes all components necessary for use
in these two modes. A significant feature of the apparatus is that
all necessary components are stored within one enclosure.
In a particularly preferred form of the invention, the functions of
circuits 164, 166, 168 and 182 are effected by a microprocessor,
such as type CDP 1802, operating under the control of a program
source such as, for example, a programmable read only memory
(PROM), an erasable programmable read only memory (EPROM) or the
like.
FIG. 6 illustrates an alternative case construction. Case 230 has a
carrying handle 232 and a hinged lid or door 234. Case 230 is
formed with an internal compartment 236 shaped and sized to receive
the detector 12 in a snug fit relation. A detector holder 238 is
removably mounted in the compartment by means of tabs 240 extending
from the case and transverse pins 242 extending from the holder.
The pins permit pivotal movement of the holder within the case so
as to facilitate insertion and removal of the detector from the
case 230. A jack 244 is secured to the holder for electrical
connection to plug 46 of detector 12 and is connected to the
electrical circuit of the detector and alarm unit 10 as explained
earlier with reference to FIGS. 1-5.
Case 230 is formed with an external air intake and control device
250 which is in fluid communication with compartment 236 and with
an air outlet passage 252 for exhausting air from the compartment
to the exterior of the case. The case also includes an internal
liquid crystal display 254 for either semiquantatively or
quantatively displaying the concentration and identity of a
detected chemical agent, an ON/OFF switch 256, a buzzer or horn 260
and a light 262. Switch 256 is mounted on the exterior surface of
the case. Volume and intensity control knobs 268 and 270 are
mounted in the case as shown. An actuating element 264 of a
detector presence sensor is operably mounted within compartment 236
and serves to automatically deactivate the circuitry within case
230 when detector 12 is removed from case 230.
It will be understood that various modifications and alterations
may be made to the aforementioned device without departing from the
spirit of the invention.
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